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OLIVE OIL

highly mobile, yellow, almost odourless, and of sweetish taste : it should have
D =0-914-0-920, iodine number = 94-100, saponification number = 190-195,
and should be incongealable at — 10° and should respond to the above reaction
with nitric acid.

OLIVE   OIL

This is obtained from the fruit of Oka europea, and is pale yellow or
sometimes greenish and with characteristic smell and taste ; about 15
grams of the oil dissolve in 1000 c.c. of absolute alcohol at 13-15°.

With Heydenreich's, Hauchecorne's, Brulle's or Bellier's reagent it
gives a pale-yellow or greenish coloration, excepting with very old and
rancid oils, which yield more or less deep orange tints. The characters of
the oil are given in Table XLIV.

Qlive oil may be adulterated with various seed oils, especially with
arachis, cottonseed, sesame, colza, ravison or soja-bean oil, and less frequently
with maize, poppyseed and other oils. Adulteration with lard oil and with
mineral oils has been observed, but only in exceptional cases.

1.  Tests and Determinations.—'Analysis of olive oil, with the aim
of ascertaining the quality and purity, includes mainly the following :

(a)  Examination of the objective properties, that is, the aspect (lim-
pidity), colour, smell and taste.    The odour is brought out well by rubbing
a few drops of the oil between the hands and smelling the latter.    The
odour and taste indicate the fineness of an oil, its state of preservation and,
with much practice, its purity.

(b)  Determinations:   solidifying point of the oil and the melting and
solidifying points of its fatty acids;   the specific gravity ;   the refraction
on the Zeiss butyro-refractometer at 25°;   the Maumene number;   the
acid, saponification and iodine numbers.   All these are made by the methods
described in the general part of the present chapter (excepting the butyro-
refractometer reading, for which see Butter, Vol. II).

(c)  Elaidin test (see General Methods, 24).

(d)  The arachidic and lignoceric acid test and the Tortelli and Fortini
tests for eracic acid (see Arachis Oil and Colza Oil).

(e)  The colour reactions of Heydenreich, Hauchecorne, Bralle", Bellier,
Milliau, Halphen, and Villavecchia and Fabris (see General Methods, 23 ;
also Cottonseed Oil and Sesame Oil).

(/) With industrial olive oils, determinations of the moisture and ex-
traneous impurities are necessary (see General Methods, i), and it is
sometimes required to ascertain if the oil has been extracted with carbon
disulphide (see later, 8).

2.  Detection of Extraneous Oils.—The various foreign oils which
may be mixed with olive oil are detected as follows :

1.  ARACHIS OIL :   by the presence of arachidic and lignoceric acids,
the quantity of which gives an approximate measure of the amount of the
oil (see Arachis Oil).

2.  COLZA OR RAVISON OIL : by the Tortelli and Fortini test (see Colza
Oil).   In considerable proportion it lowers the melting and solidifying points